fix: Initialize audioplayer instances sequentially (#1941)

# Description

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When creating lots of audio pools, an "Unknown Error" can happen if too
many players are loaded concurrently. By breaking the instantiation of
new players into a serially-loaded structure, we can load 100s of
players and effectively remove this edge case.

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---------

Co-authored-by: Lukas Klingsbo <lukas.klingsbo@gmail.com>

Author: gnarhard

packages/audioplayers/lib/src/audio_pool.dart

@@ -67,9 +67,11 @@ class AudioPool {
       audioContext: audioContext,
     );
 
-    final players = await Future.wait(
-      List.generate(minPlayers, (_) => instance._createNewAudioPlayer()),
-    );
+    final players = <AudioPlayer>[];
+
+    for (var i = 0; i < minPlayers; i++) {
+      players.add(await instance._createNewAudioPlayer());
+    }
 
     return instance..availablePlayers.addAll(players);
   }